The present invention relates to a device for dismounting the cranks from the bottom bracket bearing axle of a bicycle.
Conventionally, the procedure to dismount the crank of a bicycle pedal from the bottom bracket bearing axle is not so easy. As illustrated in FIGS. 1, 1A, 1B, 1C, and 1D, the crank is dismounted by: using a L-shaped hexagon wrench to remove the crank lock screw from the crank and the bottom bracket bearing axle of the bottom bracket, then using a spanner to turn the hexagonal head of a hollow, internally threaded screw element so as to drive the outer thread of the hollow, internally threaded screw element into the screw hole on the crank, and then using the spanner to drive a socket head screw rod into the inner thread of the screw element so as to turn the crank away from the bottom bracket bearing axle in the reverse direction.
The aforesaid procedure is complicated because at least two spanning tools must be used. Because the outer thread of the socket head screw rod must be sufficient for turning the crank out of the bottom bracket bearing axle, the socket head screw rod can not be shortened. Therefore, it is inconvenient to carry the elongated socket head screw rod and at least two spanning tools.